Such ceramic tiles are well known. ES 2 196 991 describes a method of manufacturing ceramic tiles wherein the pattern is printed by means of screen printing or rotary serigraphy. EP 1 038 689 describes a digital printing technique for decoration of ceramic tiles, for example with a marble motif, in which a multicolor printing is effected in a single pass of the tile underneath a plurality of printing modules. The printing is effected before a first baking or between successive bakings. Although intricate patterns can be created with these techniques, the obtained surface of the ceramic tile is monotonous. CN 103241049 A shows an example of the intricacy that can be obtained with marble motifs.
CN 203080849 U describes an equipment for producing a full polished glaze porcelain tile. This equipment comprises a green brick processing equipment for producing a ceramic base layer, a cover glaze layer is sprayed and an pattern may be printed using an inkjet printing equipment. The equipment further comprises a kiln for firing the tiles.
From DE 31 13 661 A1 it is known to provide the ceramic base layer with a chamfered perimeter. From GB 1 320 637 it is known to provide a surface of a tile with a relief. The tiles from these documents do not feature prints, the obtained relief is rather coarse and each tile features an identical relief. Such technique, in particular such relief, is hence not suited for ceramic tiles that imitate natural products such as wood and stone.
U.S. Pat. No. 8,507,098 and BE 1019265 describe examples of glaze layers applied to ceramic base layers and methods of applying glaze. In these cases it concerns basically so-called dry glazes. JP 3-150283 discloses dry as well as wet glazes for ceramic tiles, wherein a smooth surface of the cover glaze layer is obtained after a pressing operation.
Ceramic tiles having a printed pattern showing a wood grain are known as well. Such tiles often have a rectangular and oblong shape with the grain lines running substantially in a longitudinal direction. The relief provided on the surface of such tiles, if any at all, is coarse and appears artificial. When no relief is applied, or only random relief features, the tiles may look glossy when viewed against light, and appear as a white surface due to the mirror-like light reflection on the glaze layer.
Ceramic tiles of rectangular and oblong shape bring about problems in installation. Such ceramic tiles may be somewhat domed and laying the tiles next to each other in an offset relationship creates height differences which are clearly noticeable especially when viewed against the light. An offset relationship between installed tiles in adjacent rows is especially desirable where the tiles have a printed pattern showing a wood grain.